The present invention relates to the use of CXCL11 for the treatment of inflammatory diseases in general and Multiple Sclerosis in particular.
Chemokines constitute a family of small structurally cytokine-like, secreted proteins that regulate cell trafficking. They are produced and secreted by a wide variety of cell types in response to early inflammatory mediators, such as IL-1β or TNF-α, and in response to bacterial or viral infection. Chemokines function mainly as chemoattractants for leukocytes, recruiting monocytes, neutrophils and other effector cells from the blood to sites of infection or damage. They can be released by many different cell types (e.g. macrophages) and can mediate a range of pro-inflammatory effects on leukocytes, such as triggering of chemotaxis, degranulation, synthesis of lipid mediators, and integrin activation.
Chemokines can be subdivided into four classes, the C, C—C, C—X—C and C—X3-C chemokines, depending on the number and arrangement of the conserved amino-terminal cysteine motifs, where “X” is a nonconserved amino acid residue. The interaction of these soluble proteins with their specific receptors, which belong to the superfamily of seven-transmembrane domain G-protein-coupled receptors (GPCRs), mediate their biological effects resulting in, among other responses, rapid increase in intracellular calcium concentration, changes in cell shape, increased expression of cellular adhesion molecules, degranulation, and promotion of cell migration.
The chemokine receptor CXCR3, also referred to as G protein-coupled receptor 9 (GPR9) and CD183, is predominantly expressed on inflammatory effector T cells, including Th1 cells [Qin et al., J Clin Invest (1998) 101:746-54; Sallusto et al., J Exp Med (1998) 187:875-83] as well as the newly defined IL-17 producing Th17 cells [Nakae et al., J Leukoc Biol (2007) 81:1258-68], but is also expressed on other lymphocytes, including B cells and NK cells [Sallusto et al., supra]. CXCR3 is highly induced following cell activation. Three chemokine ligands compete for binding to this receptor: CXCL9 (MIG), CXCL10 (IP-10) and CXCL11 (I-TAC) [Colvin et al., J Biol Chem (2004) 279:30219-27]. These ligands bind different epitopes on CXCR3, yet CXCL11 binds CXCR3 with higher affinity than CXCL9 and CXCL10 [Cole et al., supra; Tensen et al., J. Invest. Derm. (1999) 112:716-722]. CXCL11 may antagonize the function of the other two CXCR3 ligands since it rapidly leads to receptor internalization, which thus becomes inaccessible to the other CXCR3 ligands [Colvin et al., supra].
Multiple sclerosis (MS) is an inflammatory, demyelinating disease of the central nervous system (CNS). MS and its animal model, experimental autoimmune encephalomyelitis (EAE), are believed to result from autoimmune mediated activated immune cells, such as T- and B-lymphocytes as well as macrophages and microglia, and is considered to be an inflammatory neurodegenerative disease. Pathologically, MS is characterized by perivenous infiltration of lymphocytes and macrophages into the CNS parenchyma, resulting in demyelinative lesions termed plaques. These plaques, which are the hallmark of MS, are associated with oligodendrocytes death, axonal damage and neuronal loss. The inflammatory cell recruitment from the vascular bed to the perivascular space, and from there on to the CNS parenchyma, is the result of a multi-step process, which is orchestrated in part by chemokines.
CXCR3 has been previously implicated in the pathogenesis of MS [Sorensen et al., J Clin Invest. (1999) 103(6):807-15]. CXCR3 has been shown to be expressed on lymphocytic cells in virtually every perivascular inflammatory infiltrate in active MS lesions [Sorensen et al., supra]. Furthermore, elevated levels of the two CXCR3 ligands, CXCL9 and CXCL10, were found in the cerebrospinal fluid (CSF) of subjects during MS attacks which are probably accountable for the chemoattraction of CXCR3 expressing cells (e.g. CD4+ T cells) from the blood circulation into the site of inflammation [Balashov et al. Proc Natl Acad Sci USA (1999) 96:6873-8; Sorensen et al., supra]. Additionally, in EAE induced mice, administration of anti-CXCL10 antibodies decreased clinical and histological disease incidence, severity, as well as infiltration of mononuclear cells and Th1 cells into the CNS [Fife et al, J Immunol (2001) 166:7617-24]. Taken together, these findings provide strong cumulative evidence supporting a pivotal role for CXCR3/CXCL10/CXCL9 axis in T cell recruitment to the brain in MS. Yet the role the CXCR3/CXCL11 axis plays in MS is still vague.
There is substantial evidence to support the hypothesis that CXCL11 is involved in MS pathogenesis. For example, Hamilton et al. have shown elevated levels of murine I-TAC mRNA in CNS of EAE induced mice [Hamilton et al., Scand J Immunol. (2002) 55(4171-7].
Lazzeri and Romagnani have proposed the chemokine CXCL11 as a possible therapeutic target in multiple sclerosis, however, they in fact teach away from using CXCL11 for MS treatment as they propose treatment of MS by using drugs that block CXCL11 activity [Lazzeri E. and Romagnani P., Curr Drug Targets Immune Endocr Metabol Disord. (2005) 5(1):109-18].
Clark-Lewis et al. constructed a potent antagonist for the CXCR3 receptor which enabled them to explore the structure-function relationship of CXCR3 with its ligands, in particular I-TAC. The antagonist was obtained by NH(2)-terminal truncation of I-TAC. This molecule (I-TAC (4-73)), lacked the first three residues and was shown to comprise no agonistic activity. Instead it was shown to compete with I-TAC for the binding to CXCR3-bearing cells, inhibiting cell migration and inhibiting calcium changes in CXCR3 expressing cells in response to stimulation with CXCR3 chemokines. The I-TAC antagonist was not contemplated for therapeutics [Clark-Lewis et al., J Biol Chem. (2003) 278(1):289-95].
U.S. Pat. No. 6,869,606 discloses biotinylated-I-TAC complexes which maintain their functionality (e.g., binding to CXCR3 and inducing chemotaxis). U.S. Pat. No. 6,869,606 does not mention Multiple Sclerosis as a potential target disease for such complexes.
U.S. Publication No. 20060257359 discloses means of modulating phenotypes of macrophage related cells for the treatment of diseases, such as Multiple Sclerosis. U.S. Publication No. 20060257359 teaches that modulation of the cellular phenotype may be accomplished by introducing effectors (e.g., proteins, antibodies or RNA molecules) to macrophage related cells thereby altering gene expression and cell phenotype (e.g., secretion of cytokines or cell migration). Amongst a long list of potential effectors, I-TAC is specified therein. U.S. Publication No. 20060257359 describes treatment of a great number of autoimmune diseases yet it does not specify which diseases may be alleviated by up-regulation or down-regulation of I-TAC. In addition, U.S. Publication No. 20060257359 does not provide any experimental support to indicate treatment of MS with I-TAC.
PCT Publication No. WO06125077 discloses a non-natural CXCR3 polypeptide receptor ligand wherein the N-loop domain is from I-TAC for treatment of fibrotic disorders, angiogenic disorders and cancer. Treatment of MS was not contemplated.
PCT Publication No. WO05016241 discloses a synthetic CXCR3 polypeptide ligand for treating fibrotic disorders, angiogenic disorders, cancer and bacterial infections. This invention describes the use of I-TAC consensus sequence (amino acid residues which occur in I-TAC) which include or lack a signaling sequence. Thus, such CXCR3 polypeptides may function as agonist or antagonists of CXCR3. Treatment of MS was not contemplated.
There is thus a widely recognized need for, and it would be highly advantageous to have CXCL11 polypeptides that can be used in the treatment of Multiple Sclerosis.